1 everything is an object (class instances)
2 methods depends upon class of the instance
3 int,str and tuple are immutability, dict and list are mutable
4 dict keys are unique but series allows duplicate
5 list comprehension
6 slice of dict, str, list
7 dynamically typed
8 iterables are str, list, dict but int are not
9 functions are first class objects and can be applied just like built-in classes

date -d"-1 day ago" +'%b%d'

equals to

mysql -Bse"select date_format(date(date_add(now() , interval 1 day)),'%b%d')"

You can write multi line comments in a stored procedure by following mysql to think that it is a version specific code.

/*!9999
Multi line comment, retained by mysql
not executed till it reaches the mysql version 9999 :))
*/

Here are 5 steps to add any API to your slack channel.

A) Click on "Build" button on App Directory page of slack.
B) choose "Make a Custom Integration" button
C) select Slash Commands
D) Create a new command called /dest2 and add the URL mentioned above
E) Choose GET Method and save the command.

This bookmarklet will help to quickly access stack pages linking to current page

stack link

#### create bucket
aws s3 mb s3://johntest123/

#### rsync all files from a given folder to S3 bucket:
aws s3 sync /home/ec2-user/ s3://johntest123/

#### Remove bucket
aws s3 rb --force s3://johntest123/

If apache docker container does not start then make these changes...

vi /etc/sysctl.conf
net.ipv4.ip_forward = 1
fs.file-max = 50000000

Reboot or restart service:
sysctl -p

If pip is not installed, then the following command will not work

pip install awscli

We need to install pip from EPEL like this..

yum install epel-release
yum install python-pip
_____

remove quotes from mysql dump file
cat merged.txt | tr -d \'\" > mergedx.txt

Use this command to convert private key to public key.

ssh-keygen -y -f dec15a.pem > dec15a.pub

Now upload the new public key to list of keys on Amazon so that you can connect to your instances in that region using the same pem key.

We can re-create mysql users using the percona utility.

wget percona.com/get/pt-show-grants

chmod 777 pt-show-grants

./pt-show-grants